Metal door construction



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Sept. 20, 1949. K. H. MILLER ETAL 5 Sheets-Sheet 2 ept. 16. 1944 Karl HMiZLeP' nd Ronald R.Magaw Sept 20, 1949 K. H. MILLER E-r AL 2,482,592

METAL DOOR CONSTRUCTION 5 sheets-sheet s Filed Sept. 16, 1944 Sept' 20 1949- K. H. MILLER ET A1. 2,482,592

METAL DOOR CONSTRUCTION Filed Sept. 16, 1944 5 Sheets-Sheet 4 /ZZ /9 J,

Las zzg F Z6 Sept. 20, 1 949.

K. H. MILLER ET AL METAL DOOR CONSTRUCTION Filedy Sept. 16, 1944 5 Sheets-Sheet 5 2a 4 ze aus@ Ronald' RJVagaw Patented Sept. 20, 1949.

Marsi. noon coNs'raUc'noN mi n. inner, North canton, nu annals a.

mi', oorporated, Ohio Canton, Ohio, asaignors to Diebold, In-

Canton, Ohio,4 a corporation of l Application September 16, 1944, Serial No. 554,4*41

l The invention relates to metal doors and particularly to a hollow sheet metal door of iiush or substantially ilush type.

Sheet metal doors have been made for many .years, but they have been relatively expensive to manufacture, they are relatively heavy, and numerous fabricating problems are encountered, particularly in the manufacture of the so-called iiushtype of door.

AThe conventional flush type sheet metal door heretofore made has had a series of internal stiifeni'ng members extending from top to bottom of the door at spaced intervals throughout the width of the door. Face plates are secured-in some manner to the spaced` members.; Some crosswise stiffness and rigidity is provided by closuremembers extending across the top and bottom of the door. 'l

However, the forces to which ali doors are usually subjected by opening, closing o r slamming tento bend such prior doors crosswise where they are weakest rather than lengthwise where they are strongest. In attempting to overcome these difficulties and to provide more rigidity and stiffness, the prior doors have been made of relatively heavy sheet metal, which increases the cost and weight of the same; but even so the doors frequently are non-rigid and have a corner weave.

In these prior flush type doors, the vertical stiiiening members resist bending lengthwise, the relatively heavy face plate and end closure members resist bending cros'swise, and the face plates resist sagging; but there is little if any resistance to diagonal bending except when thick face plates are used. Neither of the members, with the exception noted. cooperates with any other member to resist the force that the other member is primarily designed to resist.

Moreover, in some prior sheet metal doors, the outer faceplates are secured to the spaced upright stivloning members by spot welding one face plate at 'a time to the upright members. This procedure is costly, and in addition, extensive finishing operations must be performed to dress Vthe spot welds so that-they do not appear as imperfections on the finished outer door surfaces.

Accordingly, such doors have only been used to a limited extent because of their high cost due to the heavy gauge metal required in their manufacture and the fabricating dimculties encountered; because of high shipping costs due to the heavy weight of the doors; and because of high installation costs requiring heavy door frames to sustain the heavy weight of the doors.

i can. (ci. iss-m Other typesof metal doors have been made which are provided with vertical and cross bracing. However, such doors have required bolts or rivets or tie rods to assemble the bracing, and to assemble the face plates to the bracing. This constructionmaybe satisfactory for installation in factories orwarehouses but it is not satisfactory in the construction of hotels, apartment houses, homes and the like.l

Other types of metal doors have been made in which separate bracing members are separately secured in some manner to the face plates, and

when so secured, they constitute a frame for the face plates through the medium of their connection with the face plates. This construction may be satisfactory in some instances, but its stiffness and rigidity is dependent upon the thickness of the face plates. Thus such doors require heavy face plates and have the same high cost and heavy weight discussed above.

Accordingly, itis a primary object of the present invention to substantially reduce the weight and the manufacturing, shipping and installation costs of sheet metal doors, and at the same time to provide a stronger door having the desired or required stiffness and rigidity both longitudinally and crosswise of the door.

Furthermore, it is an object of the present invention to provide a new sheet metal door construction which eliminates the use of any bolts, rivets, tie rods and the like for fabricating the door.

Also, it is an object of the present invention to provide a new sheet metal door construction whose component parts have an extremely simple design and shape and which are easy and -inexpensive to fabricate and assemble.

Doors for building construction must be made and stocked in a multitude of sizes varying in Width or length or both; and this situation increases the complexity of the problem presented.

It is therefore a further object of the present invention to provide a new sheet metal door construction which eliminates die changes or separate sets of dies for making doors of different sizes.

Likewise it is an object of the present invention members are welded together to form an integral,

- rigid, self-sustaining, inner frame which has great stiffness, especially crosswise where most needed, and which may be accurately squared and trued during manufacture so as to retain these properties when the self-sustaining frame unit is completely fabricated. A relatively thin sheet metal skin is then applied to the inner, selfsustaining, rigid frame by projection welding both skin faces to the frame at one time thereby reducing welding costs, avoiding welding difficulties and eliminating vextensive finishing operations for dressing the welds. The sheet metal door when completed may be a ush type door, or a door with either a raised or a depressed center panel, or a door with grooved, fluted or reeded surfaces; and any such type of door may have any desired size.

In accordance with the present invention, the structure of the door and its inner self-sustaining frame is such that the door may be dip painted to properly coat and protect all inner and outer metal surfaces at minimum cost.

Accordingly, it is a further object of the present invention to provide a new sheet metal door construction including an inner, integral, rigid, self-sustaining frame and a thin sheet metal skin Welded to the frame.

It is a further object of the present invention to provide a new inner, integral, rigid, self-sustaining frame for a sheet metal door formed of sheet metal channel members withA a new joint construction between the frame channel members whereby a rigid joint is provided.

Also, it is an object of the present invention to provide a new sheet metal door construction including an inner, rigid, self-sustaining frame so constructed that a thin sheet metal skin may be secured to the frame, by projection welding, both sides at one time.

Also, it is an object of the present invention to provide a new sheet metal door construction which may be dip painted at minimum cost to protectively coat all inner and outer surfaces of the door.

Likewise, it is an object of the present invention to substantially reduce the cost of sheet metal door manufacture by utilizing an inner, rigid, self-sustaining frame of simple design and construction; by utilizing thin skin-like sheet metal for facing the frame; by projection welding the door skin to the frame both sides at once without excessive welding finishing costs; and by utilizing dip painting for protecting the metal surfaces.

In the conventional flush type, sheet metal doors heretofore made, the heavy face plates intended to give stiffness and rigidity crosswise of the door are in fact merely held apart by the vertical members connected to the face plates. In such constructionl there is no effective means to prevent sagging of the door in the plane of the door, nor to prevent flexing of the plane of the door diagonally thereof.

As indicated, the integral, rigid, self-sustaining frame utilized in accordance with the present invention has great stiffness crosswise because of the horizontal frame members and has great stiffness lengthwise because of the vertical frame members. Ordinarily, such a frame when made of thin gauge channel members might sag in the plane of the frame or iiex out of plane diagonally unless the frame is provided with diagonal bracing members. y

However, in accordance with the present invention, the necessity for diagonal bracing members in the inner frame is eliminated because when the outer skin is applied to and welded to the faces of the frame, the skin functions in the same manner as diagonal bracing members. Thus, the completed door, with the skin welded to the channel faces of the horizontal and vertical members of the inner rigid frame, is rigid in all directions, not only against vertical and crosswise bending but also against sagging in the plane of the door or diagonal flexing; and this result is accomplished without the use of any diagonal frame' bracing members. Moreover, this result does not require the use of heavy face plates but is accomplished with the light gauge metal skin facing material comprehended by the present invention. In other words, in accordance with the present invention, each of the parts of the completed door functions itself or in cooperation with one or more of the other parts to resist all of the strains to which the door may be subjected, and the door therefore has great rigidity even though light in weight and formed of light gauge metal.

Accordingly, it is a further object of the present invention to provide a new sheet metal door construction including an inner, integral, rigid, selfsustaining frame and a thin sheet metal skin Welded to the frame in which all parts of the completed door function with each other to provide a door having great rigidity in all directions.

Finally, it is an object of the present invention to provide a new sheet metal door construction having all the advantages and characteristics set forth and eliminating all of enumerated prior art difficulties, disadvantages and objections.

These and other objects and advantages apparent to those skilled in the art from the following description and claims may be obtained, the stated results achieved, and the described difficulties overcome, by the devices, constructions,

arrangements, combinations, sub-combinations,

parts and elements which comprise the present invention, the nature of which is set forth in the following general statement, preferred embodiments of whichillustrative of the best modes in which applicants have contemplated applying the principles-are set forth in the following description and shown in the drawings, and which are particularly and distinctly pointed out and set forth in the appended claim forming part hereof.

The nature of the improvements of the present invention may be stated in general terms as preferably including in sheet metal door construction, an inner, integral, rigid, self-sustaining frame formed of horizontal and vertical channel-shaped sheet metal members; the channel webs being engaged and other portions of the channels abutting at each joint between the channel members to provide the frame and each joint thereof with rigidity and stiffness; the vertical frame members preferably being spaced inward from the edges of the completed door; spaced perforations in the webs of the channel members; spaced welding projections formed in the outer faces of the frame channel anges and substantially in the plane of the channel webs; vertical stile-like channel facing members projection welded to the vertical frame members and to certain of the horizontal frame members; and center panel facing members extending between the vertical channel facing members projection welded selectively to the horizontal frame members or to the horizontal and vertical frame members.

By way of example, preferred embodiments of 1 theimproved sheet metal door construction are illustrated in the accompanying drawings forming part hereof wherein:

Figure 1 is a somewhat diagrammatic front elevation of the improved door construction;

Fig. 2 is a front elevation of the inner, integral, rigid. self-sustaining frame incorporated in the improved door construction;

Fig. 3 is a section taken on the line '8-4, Fig.

2 looking toward the bottom channel frame A member;

Fig. 4 is a section taken on the'line'4-4, Fig. `2 looking toward one of the intermediate channel frame members;

Fig. 5 is a fragmentary side view looking in the direction of the arrows 5 5, Fig. 2;

Fig. 6 is an elevation of the parts shown in Fig. 5:

Fig. 7 is al fragmentary sectional view in the direction of the arrows 1-1, Fig. 3;

Fig. 8 is a fragmentary side elevation of the parts shown in Fig. '1;

Fig. 9 is a fragmentary perspective view, with parts broken away and in section, of one corner of the improved door construction;

Fig. 10 is a section through the theline IIl-I9,Fig.1;

Fig. 11 is an enlarged fragmentary sectional view of certain of the parts shown in Fig. 10;

Figs. 12, 13, 14, 15, 16, and 1'7 are views similar to Fig. 11 showing modifications of the door construction to present different door appearances;

Fig. 18 is a fragmentary side elevation of a portionf of one of the channel frame members illustrating one mode of forming projections for projection welding the outer door skin to the inner door frame;

Fig. 19 iiatol plan trated in 1 Fig. 20 is a section taken on the line 22-20,

19; FigFig. 21 is a view similar to Fig. 18 showing a modified form of construction;

Fig. 22 is a plan view of the structure shown in Fig. 2l:

Fig. 23 is a fragmentary perspective view, with parts broken away and in section, as on the line 28-23, Fig. 22;

Fig. 24 is a view similar to Fig. 18 showing another modifled form of construction;

Fig. 25 vis a plan view of structure Fig. 24;

Fig. 26 ls a section taken on the line Fig. 25;

Fig. 2'1 is a fragmentary sectional view taken on the line 21-2'I, Fig. 1 illustrating one manner of attaching a hinge to the door;

Fig. 28 is a section taken on the line 28-28,

door taken on view of the structure illusshown. in

Fig. 27:

Fig. 29 is a side elevation of the parts shown in Figs. 27 and 28;

Fig. 30 is a view similar to Fig. 21 showing a modified form of construction;

Fig. 31 is a side elevation, with parts broken away and in section, of the structure shown in Fi 30;

'ig. 32 is a fragmentary sectional view taken on the line 32-32, Fig. 1, illustrating one manner of providing for mounting a lock on the door.

Fig. 33 is a section taken on the line 83-48, Fig. 32: and

Fig. 34 is a side elevation of the parts shown in Figs. 32 and 33.

Similar numerals refer to similar parts throughout the drawings.

The improved door construction shown somewhat diagrammatically in Fig. l is indicated generally at I and includes an inner, integral, rigid, self-sustaining frame indicated generally at 2, and outer skin facing stile-like channel members 8 and 4 and skin facing center panel members l.

The inner, integral, rigid, self-sustaining frame 2, best illustrated in Figs. 2 through 9 includes a horizontal top channel member I, a horizontal bottom channel member 1, vertical channel members 8 and 9, and intermediate horizontal channel members I9. The ends of the vertical channel members B and 9 are connected by joints I I to the top and bottom horizontal channel members I and 1 at places spaced from the ends of members 4 and 1 so that in the completed frame, the vertical frame members 8 and 9 are spaced inward from the vertical edges of the completed door. The ends of the intermediate horizontal frame members Il are connected by joints I2 to the vertical Imembers 8 and 9 at spaced, places intermediate the ends of the members 8 and 9.

Each of the joints II and I2,is stiff and rigid as hereinafter described so that the frame 2 when completely manufactured is stiff, rigid, true and square.

Each of the frame members 9, 1, 8, 9, and II is made of sheet or strip metal rolled, pressed, drawn or otherwise formed to channel shape.

The top and bottom channel members 9 and 1 are similar in shape. and each end is similarly formed with inwardly pressed recesses I2 in the channel flanges I4 in the region of each joint II, spaced from each end I5 of members 6 and 1. A series of holes I6 are formed at spaced intervals in the webs I1 of members 6 and 1; and half round notches` I8 are also provided at the ends I5 of members 8 and 1. An aperture I9 is also provided in the channel web I'I lin the region of y' cut from the web 2| and flanges 22 thereof. Thus,

at each end of each member 8 'and 9, notches 23 are cut, leaving flange ends 24 and a tongue 25 at each end of the web 2|. The tongues 25 are of such length and width that when the ends 24 (Figure 9) of the flanges 22 of members 9 and 9 rest upon the free edges of the recessed flange portions I3 of members 8 and 1, the tongues 25 extend through openings I9, and through and between notches 2l.

The tongues 25 are tack-welded at 26 to the webs II of members 9 and 1 to form the joints II and the flange ends 24 may be tack-welded at 26a to the recessed ange portions I3. When the joints II are formed, the interengagement between the web tongues 25 and web notches 2l prevents the members 8 and 9 from twisting with respect .to the members 6 and 1; andthe end flange abutment 24 of members 8 and 9 with the depressed flange portions I3 of members 8 and 1,

' together with the welds 2B and 26a, prevent members 8 and 9 from angling with respect to members 6 and 1 so that the joints II between the members 6, 1, 8, and 9 are rigid and truly right angularly held.

The webs 2i of up-rlght members 8 and 9 are also formed at spaced intervals with holes 21 provided with opposite notches 28. The intermediate channel members I0 are also each similar in shape and each have the` same end formations. Notches 29 are cut in the flanges 89 and into the web 3| of the members I8 leaving a tongue 32 extending from each end of the webs 3|.

In assembling the intermediate members I with the vertical members 9 and 9, the tongues 32 are inserted through holes 21 and through and between notches 28 in members 8 and 9. Also, the edges of notches 29 in members I0 abut the flanges 22 of members 8 and 9 in forming the joints I2. The tongues 32 are tack-welded at 33 to the webs 2Iof members 8 and 9 and the notched edges 29 are tack-welded at 33a. to the flanges 22. The interengagement between tongues 32 and notches 28 prevent twisting of the members I0 with respect to members Il. and 8; and the abutment between notched edges 29 and flanges 22, and also the welds 33 and 33a prevent angling of the members I0 with respect to the members 8 and 9. Thus, the joints I2 when formed also rigidly hold the members in truly right angular shape.

In assembling the inner, integral, rigid, selfsustaining frame, the members 6, 1, 8, 9, and I0 are placed in the position shown in Fig. 2 with the tongues 25 extending into notched apertures I9-2Il and the tongues 32 extending into notched apertures 21-28. The members so assembled, are rigidly held in a jig in truly square relation and the welded joints 26, 26a, 33 and 33a are made while the members are so held. Upon completing these welding operations, the frame 2 becomes an integral frame, truly square and rigid because of the channel shape of its members and because of the rigidity of the joints II and I2; and the frame has great crosswise and vertical stiffness. A series of apertures 34 are also provided in spaced intervals along the Webs 3l of each channel member I0.

The particular shape of the round notched holes I9-20 and 21-28 and of the tongues 25 and 32 provides for quick assembly of the joints Il and I2 without special tools or jigs; the only jig required being one for holding the assembled frame members square while forming the tackwelds 26, 25a, 33 and 33a.

Each oi the members 6, 1, 8, 9, and Ill is provided with a Series of welding projections at spaced intervals in each channel ange in regions adjacent the channel web. For clearness, these projections are not shown in Figs. l to 8, inclusive, but are illustrated in Fig. 9 and in several ways in Figs. 18 to 26, inclusive. Referring rst to Figs. 18, 19 and 20, a series of spaced, parallel, closely adjacent grooves 35 are formed inward in the web of each channel member, such as the lweb 2l of channel member 9, by striking the channel member with a rounded or sharp nosed die. In forming the grooves, the metal in the channel corners between the flanges 22 and web 2I distorts or is forced outwardly to form projections 36 well shown in Fig. 20. Figs. 2l, 22, and 23 illustrate a modification in which only single grooves 35 are formed at spaced intervals to provide projections 36.

Figs. 24, 25, and 26 illustrate a further modication in which the corner between the flanges 22 and web 2I of channel members such as 9, are struck from the inside with a pointed die to form projections 31.

As stated, welding projections such as 36 or 31 are formed at intervals along the length of each of the frame channel members 6, 1, 8, 9, and I0.

The outer skin facing stile-like channel members 3 and 4 are similar in shape and may be made of sheet or strip metal, rolled pressed,

- flange edges 40 of each stile member 3 and 4 are drawn or otherwise formed to channel shape with a door edge web 38 and flanges 39. 'I'he outer edges of flanges 39 are recessed at 40'and the members 3 and 4 are cut to length. The skin facing center panel members 5 are plain rectangular metal sheets cut to size.

The stile channels 3 and 4 are slipped and telescoped over the ends of the top and bottom frame members 8 and 1 of an inner frame 2 with the recessed edges 40 located against the recessed flanges I3 of the top and bottom frame members 6 and 1 and against the flanges 22 of the vertical frame members 8 and 9. The face panels 5 are then placed between stiles 3 and 4 against the cross frame members I0, with the side edges of panel members 5 overlying the recessed edges 40 of stile members 3 and 4. The parts, thus assembled are held in a jig to maintain the assembly square and nat. 'I'he jig is associated with or forms a part of projection welding apparatus wherein welds are formed at both faces of the door at once at the location of the welding projections 36 or 31 formed along the flanges of all of the frame members 6, 1, 8, 9, and I0.

Thus, both flange faces of the top and bottom ends of each stile member -3 and 4 are projection welded at 4I to the flanges I4 at the ends of top and bottom frame members 6 and 1; and both projection welded to the flanges 22 of the vertical frame members 8 and 9 at 42 as indicated in Fig. l1. Likewise, the panel members 5 are projection welded at 43 to the flanges 38 of horizontal frame members I0 and are similarly projection welded to the flanges I4 of the top and bottom frame members 6 and 1.

Projection welding blisters 44 are also preferably provided at spaced interv-als (Fig. 9) along recessed flange edges 40 of stile members 3 and 4 so that the edges of panel members 5 may be projection welded at 45 to the stile member edges 4I) at the same time that the projection welds 42 are formed between the stile member edges 40 and the frame channel member flanges 22.

A projection Welding operation involves the passage of welding current through the members being welded and through projections formed in the surfaces of one of the members while the members 4are under pressure. The location of the welding projections 35 or 31 (as shown in Figs. 9 and 18 to 26) substantially in the plane of the channel webs of the frame members locates the channel webs of the frame members substantially directly in the line of pressure, so that maximum welding pressure may be exerted and so that the welding current h-as the shortest path of travel through the channel webs from opposite projections 36 or 31.

It is preferable to use the form of welding projections 3-6 illustrated in Figs. 18 to 23 because the grooves 35 extending laterally across the channel webs 2I stiiien the channel webs laterally for resisting the projection welding pressure.

If desired, the stiles 3 and 4 may be welded to the inner frame 2 and thereafter the panel members 5 may be applied thereto and welded to the inner frame.

The use of projection welding for assembling the skin to the door frame enables both door facings to be welded at one time and enables the welds to be formed without pitting or burning the outer surfaces of the metal and without heating the panels to a degree that might produce distortion of the metal.

We have discovered, that a door fabricated as described above, has great ness and strength in all directions even though the frame members may be made of light gauge sheet metal, as thin as 0.050" thick sheet ,metal and thinner, and even though the stiles and panels .forming fthe facing skin are made of thin gauge sheet metal, as thin as 0.035 to 0.029" thick sheet metal. Furthermore, we have discovered that the location of the vertical members 8 and 9 spaced inward from the edges of the completed door and along the inner edges of stile members 3 and 4 lprovides a decidedly stronger and more rigid doorthan is provided by locating the frame members 8 and 9 extending from the extreme ends of the top and bottom frame members 6 and 1.

Upon completion of the projection welding operations, the small V-shaped grooves 48 remaining between the edges of panel members 5 and the inner edges of flange recessed portions 40 may be filled with metal or other material yas indicated at 41 in Fig. 11 so as to provide a door having smooth, uninterrupted, flush surfaces. 'I'he outer skin surfaces may then be prepared in the usual manner for coating, but because of the use of projection welding, little if any weld finishing is required in the nal surface .preparation of the outer skin surfaces of the door.

The doors I then may be dip painted or otherwise dip coated to completely cover and protect all of the internal and external metal surfaces thereof. Thel holes I6, I8, I9, 21 and 34 in the frame members 6, 1, 8, 9, and I permit the paint or other coating liquid to penetrate into and through the interior of .the door and to cornpletely drain therefrom during any dip coating operation.

The same holes in the framemembers also permit some interior ventilation of the doors when installed in a building so as to minimize condensation on the door surfaces.

'I'he modified form of door construction illustrated in Fig. 12 is similar to that of Fig. 11 except that the inner edges of the stile flanges are not recessed and the center panels are raised from the surfaces of stile members 3 and 4, as indicated at 48, to provide a door having a raised or offset center panel and thus having a somewhat difrerent appearance than the flush door illustrated in Fig. 11. l

In the modified fonn of construction illustrated in Fig. 13, the inner edges of the flanges of the stile members 3 and 4 are reversely bent at 49 and again reversely bent at 50 to provide a channel groove 5l. The vertical edges of the center panels 5 are shaped with an offset as indicated at 52 for being received in grooves 5I. In assembling the door shown in Fig. 13, the stiles 3 and 4 are welded to the inner frame 2 and no surface finishing operation need be yperformed u-pon the welds 42 between the stiles and vertical frame channels 8 and 9. Then the center panels 5 are slipped into place or they may be bowed for entering the offset edges 52 into grooves 5|. The panel members 5 are then welded to the inner frame 2, at 43; but no welding is required between the vertical edges of the panels 5 and the stile members panel members 5 are securely held in -place in the grooves 5 l.

As shown, ithe construction of Fig. 13 also provides a flush door. The, V-shaped vertical grooves 53 may be lled with metal or other material 54 to complete the uninterrupted ush surfaces.

Fig. 14 illustrates a slight modification of the rigidity, stability. stifffil 3 and 4 because the edges of the hinge;

door structure shown in Fig. 13, in which the center panels 5 have a different edge offset formation 55, so as to provide vertical grooves 55 in the completed door.

Fig. 15 illustrates a further modification ofthe construction of Figs. 1 3 and 14 in which flat panel members 5 without any edge offsetting are assembled with stiles formed with grooves 5I This results in a door having a recessed center panel.

The doors illustrated in Figs. 16 and 17 are further modifications of the door structure of Fig. 15. In Fig. 16, the center panels 5a are fluted and in Fig. 17, the center panels 5b are reeded. Also in Fig. 17, the anges of intermediate frame members I0 are pressed inward at 30a and teleseoped between flanges 22 of vertical members 8 and 8 and spot welded thereto at 30h in forming joints I2.

The arrangement of holding the edges of the center panel 5 in grooves 5| in the stile members illustrated in the modifications of Figs. 13 to 17, inclusive, is desirable in that it reduces thenumber of welds required to hold the center panels iiat on the inner frame member 2. Also the ar,- rangement is desirable from the stand-point of a fire test in that it provides a slip Joint between edges of the center panels and the stile members which accommodates to differences in expansion and contraction of the various inner frame and skin members of the door.

The door hinge stile 4 may be prepared, prior to assembly to the inner frame2, as illustrated in Figs. 1, 27, 28 and 29.' The channel web 28 may be slit at 51' and pressed inward at 58 for each and a hinge reinforcing plate 59 may be welded to the inside of the web 38 above and below slits 51. Hinge straps 60 may then be received in the recesses formed by the walls 58 and screwed to' the reinforcement plates 59 by screws 6l.

Figs.,30 and 31 illustrate a modified form of construction for accommodating an ofl'set hinge 62. In this construction, the corners 63 ofhinge stile 4 are vrounded andthe web 64 is recessed throughout its length, as shown. A hinge reinforcement plate 65 for each hinge is welded to the stile web 64 and the offset hinge 52 is received in the stile recess 64.

The lock stile 3 may have a U-shaped lock support 66 welded within the channel prior to its assembly to the inner frame 2. The web 38 of stile member 3 may be cut out at 61 to receive a lock face plate. The lock housing may project inward through aperture 68 formed in support member 66, and holes 69 may be formed in the flanges 39 of lock stile 3 for assembling the door handle shaft to the lock housing.

The foregoing description indicates the simplicity of the manufacturing operations required for fabricating the improved doors and the simplicity of its component parts. Thus, the same die used for cutting and shaping one end of each vertical frame member 8 or 9 may be used for cutting and shaping the other end thereof irrespective of the length of the member; and each of frame members 8 and 9 are the same. Likewise, the same die used for cutting and shaping one end of each horizontal frame member I8 is also used for cutting and shaping the other end thereof and all of frame members I0 are the same. Likewise, the end formation and recessing of the flanges of similar top and bottom frame members 6 and 1 may be performed in the same die.

Each stile member 3 and 4 .for any particular ll door is the same excepting for the hardware preparation; and each center panel is the same. A

In order to change the width of a door, it is only necessary to change the cut length of frame members 8, 1. and I and the cut width of center panels 6. In order to change the height of a door, it is only necessary to change the cut length of frame members 8 and 9, stile members 3 and 4 and center panels 5. Thus, the same equipment may be used for manufacturing various sizes of doors.

Moreover, the improved inner frame construction, the construction ofl its joints, and the pro- Jection weldng of the stiles and center panels to the rigid frame provides an extremely strong door having great stiffness and rigidity in every direction formed of light gauge sheet metal, without the use of bolts, rivets or tie rods.

Moreover, the improved door construction enables dip coating to be used for protecting the metal surfaces.

Also, the improved door construction eliminates the necessity of any diagonal bracing for the door to resist sagging in the plane of the door or diagonal ilexing of the door out of its plane.

Furthermore, the use of channel shapedy frame members and of prolection weding, including the location of the welding proiections substantially in the plane of the webs of the channel members,

enables welded joints to be formed between the inner frame and outrr skin members on both sides of the door at once, with a minimum weding cost; and the inner frame channel webs withstand the pressure necessary for carrying out a projection welding operation.

Accordingly. the improved metal door construction has all of the foregoing advantages and characteristics; eliminates all of the enumerated prior art diiculties, disadvantages and objections; substantially reduces the weight and the manufacturing, shipping and installation costs of sheet metal doors; and provides a very strong door having great stiffness and rigidity in all directions formed of extremely light gauge sheet metal parts of simple design and shape.

The embodiments of the present improvements are illustrated and described herein by way of example, and the scope of the present invention is not limited to the exact details of the construction of the various parts.

In the foregoing description, certain terms have 12 been used for brevity. clearness and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art. because such words are used for descriptive purposes herein and not for the purpose of limitation, and are intended to be broadly construed.

Thus, when the term "sheet metal" is used herein and in the appended claim, that term is intended to refer to steel or other metals which may be used in the manufacture of metal doors. and the term is also intended to include metal in sheet, strip, stripsheet or extruded form.

Having now described the features of the invention, the manufacture o! preferred embodiments thereof, and the advantageous, new and useful results obtained by the improved constructions; the new and useful devices, constructions, arrangements, combinations, sub-combinations, parts andelements, and reasonable mechanical equivalents thereof obvious to those skilled in the art, are set forth in the appended claim.

We claim:

Sheet metal door construct-ion including an inner, integral, rigid frame formed of horizontal and vertical channel members with rigid joints therebetween, the webs of the channel members being formed with grooves projecting inward of the channels to provide welding projections at the ends of the grooves in the outer faces of the channel flanges substantially in the plane of the channel webs, channel shaped stiles, central panel members extending between the stiles, and the stiles and panels being welded to the flanges of the inner frame channel members by said welding projections.

KARL H. MILLER. RONALD R. MAGAW.

REFERENCES CITED The following references are of record in the iile of this patent:

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